Traditionally, sedimentation rates are measured using a Westergreen tube or pipette, that is, a thin graduated tube open at both ends. The technician first immerses such a tube in a tube or container of larger diameter containing a blood sample, then sucks up the blood from the upper end of the Westergreen tube to a predetermined upper reference graduation of the tube. The lower end of the tube is then sealed and the tube is placed on a support. The operation is repeated successively for each sample tube.
Spaced readings are then taken, the first usually at the end of one hour, and the second at the end of two hours, of the level of sedimented red blood corpuscles in each tube.
After the analysis, the used tubes are washed and cleaned for reuse.
For a medical analysis laboratory carrying out a large number of sedimentation rate measurements every day, the process thus described must be repeated as many times as there are blood samples to be analyzed. In addition to the fact that this process is relatively time-consuming, it also posed a medical danger for the technician who must draw up the blood by mouth suction from the tubes containing the samples, into the Westergreen tubes, to the appropriate level and who may, in the case of improper suction, ingest contaminated blood.
In U.S. patent application Ser. No. 560,477, filed Dec. 12, 1983 (based on French patent application No. 82 21221), applicant has already proposed a blood analysis apparatus eliminating all risk to the technician and allowing a large number of analyses to be carried out simultaneously.